Curtain walls are typically constructed of extruded aluminum frame support members having generally U-shaped channels for supporting a plurality of panel members that serve as the exterior of a building. Such panel members are most often panes of glass, but other paneled building materials such as aluminum, granite, slate, or concrete are also utilized. Such panel members are often of identical size and shape. However, near doors, opening windows, or other access points into the building, panel members of different sizes an shapes may be utilized.
More specifically, such curtain walls generally include a horizontal sill member having an upwardly facing U-shaped channel at the bottom of a wall section, a horizontal head member having a downwardly facing U-shaped channel at the top of a wall section, and a plurality of vertical mullions running between the sill and head members. Panel members are supported by the U-shaped channels of the sill member and the head member, and the vertical joints between adjacent panel members are formed at the mullions. Typically, the mullions are disposed interiorly of the sill member, the head member, and the panel members so that only the joint between adjacent panel members, and not the mullions themselves, are visible from the exterior of the building.
An exemplary, conventional curtain wall is described and shown in U.S. Pat. No. 6,158,182, the entire contents of which are hereby incorporated by reference. As described therein, and with reference to FIG. 1, a sill member 10 is illustrated for securing a curtain wall to a concrete slab 12. Although not shown in FIG. 1, a head member similar to sill member 10 secures the curtain wall to a concrete slab between floors of a building or other building structure, and a plurality of mullions span between sill member 10 and the head member. Sill member 10 is typically formed as an integral aluminum extrusion. Sill member 10 generally includes a channel section 14, an anchoring section 16 disposed interiorly of channel section 14, and a cover 18.
Channel section 14 and cover 18 cooperate to secure a panel member 20 to sill member 10. More specifically, channel section 14 includes a base 14a and two legs 14b and 14c that form a upwardly facing U-shaped channel. A support member 22 rests on the top surface of base 14a. Leg 14b has a groove 24 proximate the upper end of its interior surface, and leg 14c has a support surface 26 proximate the upper end of its interior surface. Cover 18 has a downwardly depending resilient leg 28 that engages a groove 30 on the exterior surface of leg 14c. Cover 18 also has a tongue 32. Panel member 20 is supported within channel section 14 via setting block 34 and resilient gaskets 36 and 38. Setting block 34 is disposed on the top surface of support member 22. Resilient gasket 36 has a tongue 36a that engages groove 24 of leg 14b. Resilient gasket 36 is typically pre-installed in groove 24 of leg 14b during manufacturing of sill member 10. Resilient gasket 38 has a groove 38a that engages tongue 32 of cover 18 and a surface 38b that mates with surface 26 of leg 14c. Channel section 14 further includes a plurality of support legs 40 below base 14a. 
Anchoring section 16 includes a base 16a, a leg 16b, and a plurality of support legs 42 below base 16a. Base 16a has a plurality of holes 44 spaced along its length for receiving bolts or fastening means 46, and the diameter of each hole 44 may either be substantially identical to the diameter of a threaded shank 46a of each bolt 46, or the hole 44 may be slotted to allow for horizontal adjustment of the sill position. Leg 16b has a groove 48 for receiving a tongue 49 of cover 18.
The following technique is typically used to install a panel member 20 of such a conventional curtain wall. First, sill member 10 is laid on a shim 56 in the proper position on slab 12 and is used as a template to drill holes into slab 12 for each bolt 46. One should note that shim 56 does not run continuously along the length of sill member 10. Instead, shim 56 is used at low points of slab 12 to level sill member 10, if necessary. Next, sill member 10 is removed from shim 56, and a hole 50 with a larger diameter is drilled in the place of each of the holes drilled using sill member 10. A structural insert 52 is then secured within each of holes 50 via epoxy or other conventional means. Each insert 52 has an internally threaded hole 54 for receiving bolts 46. Sill member 10 is then repositioned on shim 56 and secured to slab 12 using bolts 46. A sealant 58 is disposed on slab 12 along both the exterior and interior sides of shim 56 and a head member similar to sill member 10 may also be secured to part of the building structure using the above-described techniques. Thereafter, vertical mullions are secured between sill member 10 and the head member at appropriate intervals along the curtain wall. A support member 22 is disposed on base 14a of sill member 10, and setting block 34 is disposed on support member 20. Panel member 20 is then installed from the exterior of the building, typically first being tilted into the channel section of the head member, and then being dropped into channel section 14 of sill member 10. The cover 18 can then be installed in sill member 10, and a glazing stop is installed in the head member of the curtain wall. Finally, resilient gasket 38 is disposed on tongue 32 of cover 18 of sill member 10, and a similar gasket is disposed on the tongue of the glazing stop of the head member.
Of course, multiple panel members 20 are typically arranged side-by-side and are secured and sealed between sill member 10 and the head member in this manner, with their vertical joint overlapping at a mullion. This vertical joint must then be sealed from both the interior and exterior of the building using both resilient gaskets and/or structural silicone.
Current means of architectural glazing with metal framing generally include three types of systems: individual window units or ribbon windows; storefront or entry systems with structural capacity to span one or two vertical levels; and curtain wall systems which are self-supporting over the entire height of the building, as described above. As used broadly herein, “curtain wall” is understood to refer to all types of glazing systems with metal framing and “sill” is understood to refer to either a horizontal or vertical sill member depending upon the particular construction. Advantages of these systems over older wood or solid metal framing include increased glass areas for providing natural light to building interiors, structural capacity to support insulated glazing, and resistance to temperature and water infiltration. While such systems, and other conventional curtain walls, have proved to be reliable commercial building systems, they suffer from several drawbacks. One particular drawback of these types of systems is the limited opportunity to provide power and/or data to the predominate exterior walls of the building, unless a separate metal stud and finish partition, with conventional conduits and outlets, is created between or under the window system, which thereby requires increased labor for installation and destroys the aesthetic appeal created by the curtain wall and increased glass area.